Pathogens reproduce rapidly inside your body; they damage your cells; they produce toxins that make you feel ill. Your body reacts to pathogens and the damage they cause/toxins they make, which also makes you feel ill

Give 5 examples of things we now know we can do to reduce the spread of pathogens to lower the risk of disease, e.g. hand-washing in hospitals

Wiping work surfaces, cleaning toilets, using tissues to blow nose, washing hands before handling food, coughing with over mouth etc.

What are the 4 main ways in which infectious diseases are spread?

Droplet infection, direct contact, contaminated food and drink and through a break in the skin

What are the 3 main ways in which your body prevents pathogens from getting in?

Explain what vaccination involves and how being vaccinated can prevent a person from cathing the disease

When a person is vaccinated against a disease, they are injected with dead/inactive disease bacteria. The dead/inactive bacteria carry antigens, which cause the body to produce antibodies to attack them. If the live disease infect the body after this, white blood cells can rapidly produce antibodies to kill the bacteria

How do viruses make you ill?

By cell damage

What is bacteria?

They are very small living cells, which can reproduce rapidly inside your body

Small fragmrnts of cells (platelets) help blood clot quickly to deal with wounds

What are the 2 main types of pathogen?

Bacteria and viruses

How does bacteria make you feel ill?

By damaging your cells anf producing toxins (poisons)

When white blood cells produce antibodies, are the antibodies produced specifically to the antgen?

Yes, the antibodies won't lock on to any antigens

About how long does it take your white blood cells to learn how to deal with a new microorganism?

A few days

What does the MMR vaccine protect against?

Measles, mumps and rubella

What are common disease symptoms?

High temperature, headaches and rashes

What are disease symtoms caused by?

The toxins produced by the pathogens. The symptoms also appear as a result of the way your body responds to the damage and toxins

Why is it good if white blood cells have already produced antibodies once against a particular pathogen?

It's good as if the person is infected with the same pathogen again, the white blood cells will rapidly produce antibodies to kill it - the person is naturally immune to that pathogen and won't get ill

Name 4 diseases caused by bacteria

Food poisoning

Cholera

Typhoid

Whooping cough.

Name 7 diseases caused by viruses

Influenza (flu)

Colds

Measles

Mumps

Rubella

Chicken pox

AIDs.

Pathogens are not......they cause the.......

Disease

White blood cells do not......the pathogens, they......them

Eat, ingest

Are antibodies and antitoxins living things?

No, they are specialised proteins

Pathogens contain certain chemicals that are foreign to the body. These chemicals are called......

Antigens

What are lymphocytes?

They are a certain type of white blood cell, which can produce specific antibodies to kill a particular pathogen

How does a lymphocyte kill the pathogen?

Each lymphocyte produces a specific type of antibody - a protein that has a chemical 'fit' to a certain antigen. When a lymphocyte with the appropriate antibody meets the antigen, the lymphocyte reproduces quickly and makes many copies of the antibody to kill the pathogen

What are phagocytes?

They are a certain type of white blood cell which ingests pathogens

How can an antibody neutralise a pathogen?

They can bind to pathogens and damage or destroy them

They can coat pathogens, clumping them together so that they are easily ingested by white blood cells called phagocytes

Vaccines can contain...

Live pathogens treated to make them harmless

Harmless fragments of the pathogen

Dead pathogens

Vaccines containing harmless fragments of the pathogen acts as an antigen. Why?

When injected into the body, harmless fragments of pathogen stimulate white blood cells to produce antibodies against the pathogen

Why don’t medicines like paracetamol actually cure your illness?

Because they do not kill the pathogens that are making you ill - they are only painkillers

What is an antibiotic?

A drug that kills pathogenic bacteria in your body

How do antibiotics work?

They damage bacterial cells without damaging human cells

Who was the ﬁrst person to discover penicillin?

Alexander Fleming

What is the main difference between drugs such as paracetamol and drugs such as penicillin?

Paracetamol relieves symptoms/makes you feel better, whereas antibiotics kill the bacteria and actually make you better

How did Alexander Fleming discover penicillin?

He noticed a clear area around mould growing on bacterial plates

Why was it so difﬁcult to make a medicine out of penicillin?

It was difﬁcult to get much penicillin out of the mould and it does not keep easily

Who developed the industrial process which made it possible to mass-produce penicillin?

Florey and Chain

Explain why it is so much more difﬁ cult to develop medicines against viruses than it has been to develop antibacterial drugs

Viral pathogens reproduce inside your cells, so it is very difﬁ cult to develop a drug that destroys them without destroying your cells as well

Do painkillers have an effect on viruses?

No, they will have no effect on the viruses which have entered your tissues and made you feel ill.

What is agar jelly?

A nutrient-rich medium used to culture microorganisms such as fungi and bacteria

Why must everything be sterilised before you start a culture?

To prevent contamination by microbes already on the equipment

Why do we culture microorganisms in the laboratory?

To ﬁnd out more about them. To ﬁ nd out which nutrients they need to grow and to investigate what will affect them and stop them growing

When you set up a culture of bacteria in a Petri dish, you give the bacteria everything they need to grow as fast as possible. However these ideal conditions do not last forever. What might limit the growth of the bacteria in a culture on a Petri dish?

Using up the available food and oxygen, build up of waste products such as carbon dioxide and other toxins

Why is it important not to use antibiotics too frequently?

To prevent more antibiotic-resistant strains appearing

Is MRSA a bacterium or a virus?

Bacterium

(Use Figure 2) How could you explain the increase in deaths linked to MRSA?

Increased use of antibiotics leading to more resistant bacteria, lower hygiene standards in hospitals, people failing to wash their hands between patients, visitors bringing in pathogens to hospitals

(Use Figure 2) How could you explain the fall in deaths linked to MRSA, which still continues?

Could be an improvement in cleanliness in hospital, people being more careful about hand washing or introduction and use of alcohol gels for visitors and staff in hospitals

After a colony of bacteria is treated by an antibiotic, what percentage is killed and what percentage survive?

95% of bacteria killed are by antibiotic anf 5% survive – they have a mutation which makes them resistan tto antibiotic

Why can bacteria become resistant to antibiotics?

They can mutate - sometimes the mutations can cause them to be resistant

Do these mutations happen at a set time?

No, these mutations happen by chance and they produce new strains of bacteria by natural selection.

Why is it bad if some bacteria is resistant to antibiotics?

It means that when you treat the infection, only non-resistant strains of bacteria will be killed but the resistant bacteria will survive and reproduce meaning the resistant strain will increase - which is bad. (Example of natural selection)

If bacteria change or......they may become......to...... This means the medicine no longer makes you...... A......in a......or......can also lead to a new form of......

A chemical (protein) made by the white blood cells that target speciﬁc antigens

Give an example of one bacterial and one viral disease which you can be immunised against

Bacterial - tetanus, diphtheria etc.

Viral - measles, mumps, rubella, polio etc.

Explain how the immune system of your body works

Every cell has unique proteins on its surface called ‘antigens’. Your immune system recognises that the antigens on the microorganisms that get into your system are different from the ones on your own cells. Your white blood cells then make antibodies to destroy the antigens/pathogens. Once your white blood cells have learnt the right antibody needed to tackle a particular pathogen, they can make that antibody very quickly if the pathogen gets into your system again, and so you are immune to that disease

Explain how vaccines use your natural immune system to protect you against serious diseases

A small quantity of dead or inactive pathogen is introduced into your body. This gives your white blood cells the chance to develop the right antibodies against the pathogen without you getting ill. Then if you meet the live pathogens, your body can respond rapidly, making the right antibodies just as if you had already had the disease

Explain why vaccines can be used against both bacterial and viral diseases but antibiotics only work against bacteria

Vaccines can be made using inactive viruses or bacteria so can stimulate antibody production against either type of pathogen thereby developing immunity. Viruses reproduce inside body cells so antibiotics cannot kill them without killing the cells of the body at the same time

What is MRSA?

A serious infection that can't be treated by antibiotics

How is MRSA caused?

Hospitals use a lot of antibiotics to treat infections. As a result of natural selection, some of the bacteria in hospitals are resistant to many antibiotics. This is what has happened with MRSA

What 7 ways can we reduce the risks of mircoorganisms such as MRSA?

Antibiotics should only be used when they are really needed.

Speciﬁc bacteria should be treated with speciﬁc antibiotics

Medical staff should wash their hands with soap and water or alcohol gel between patients

They should wear disposable clothing or clothing that is regularly sterilised

Visitors should wash their hands as they enter and leave the hospital

Patients infected with antibiotic-resistant bacteria should be looked after in isolation from other patients

Hospitals should be kept clean – there should be high standards of hygiene

Microogranisms are cultured in a...

Culture medium

What does agar jelly usually contain for the microorganisms?

Carbohydrates, minerals, proteins and vitamins the microorganisms needs to grow

Is the agar jelly hot or cold when it's poured into Petri dishes?

Hot

What are inoculating loops?

They are wire loops that are used to transfer microogranisms to the culture medium when the agar jelly's set

How are antibiotics investigated by growing microorganisms on a petri dish in agar jelly?

Paper discs are soaked in different types of antibiotics and placed on the jelly - the antibiotic-resistant bacteria will continue to grow around them but non-resistant strains will die

Why is it important to sterilise equipment when growing microorganisms in a culture medium?

To stop unwanted microorganisms in the culture medium growing and affecting the results

What 3 things must be sterilised before use to prevent contamination when growing microorganisms in a lab?

The Petri dishes, culture medium and inoculating loops

Why should the Petri dish have a lid taped on when growing microorganisms in a culture medium?

To stop any microorganisms in the air contaminating the culture

Why are cultures of microorganisms kept at 25 degrees at school and not higher?

Cultures at a higher temperature, could allow harmful pathogens to grow

In industrial conditions, why are cultures incubated at higher temperatures then 25 degrees?

So they can grow faster

Why may booster injections have to be given after period of time after the vaccine?

Some vaccines wear off over time and so booster injections may need to be given to increase levels of antibodies again

Why is it good that vaccines have been produced compared to before?

They have helped control lots of infectious diseases that were once common in the UK (e.g polio, measles, whooping cough) Smallpox no longer exists thanks to vaccines

How can epidemics be prevented with vaccines?

They can be prevented if a large population is vaccinated as that way, even people who arn't vaccinated are unlikely to catch the disease because there are fewer people to pass it on

What are the 2 disadvantages of vaccines?

Vaccines don't always work - sometimes they don't give you immunity

You can sometimes have a bad reaction to one (e.g. swelling, seizures) However, bad reactions are rare